At 02:52 AM 8/4/02 +1000, you wrote:
>Morgan Olsson wrote:


>> The original failure reason i tink is that the cirquit board is covered
with some grease, and it seems something in the grease diffuses into the
gasket which then expands.
>>
>> I have also found another radial eletrolytic cap on the cirquit board
hich has also pushed itself out.

You may very well be correct, Morgan, in that the grease caused the failure
of the capacitor. In a previous life, I worked at a power supply company.
It was standard practice to run the boards through a vapor degreaser to
remove solder flux.

Someone changed brands of electrolytic capacitors at one point and a rash
of failures resulted. The failures did not happen in house. They occurred
at the customers site, from 1 to 3 months later.

It was determined that the degreaser solvent was being "soaked up" by the
sealing gasket in the end of the capacitor.  Over time, the solvent did 2
things: it caused the gasket to swell up and it slowly destroyed the
dielectric of the cap. The cap slowly lost its capacitance; some went open,
some went shorted, most failed.

Tom M.

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